Computer applies web connection that includes hardware and software to reach the objective of resource share, for example, the accessory device of computer hard disc data and printer, etc., which have already been the popular solutions in today's technology but, for the user of non-enterprise, especially for the common home computer, the web device is very expansive. Even for a small venture exclusively with its own investment or offices, the users can not afford the construction of an entire web. Because of insufficient budget, this sort of customer is very desired for the common computer devices.
Taking the printer—the most popular computer accessory device as an example, it is scarce for every computer belonging to each user to be matched with a printer respectively, so the requirement for common device is very important in consideration of economic effectiveness. Therefore, how to supply more economic and fast accessory devices that can be used commonly has already become a problem to be solved anxiously by current market and industry.
The prior technique may manipulate a printer's input/output switch by hand and since its operation is manual, so it is very inconvenient. It is more convenient to apply the software in the user's host for switching the printer. However, the internal elements of this kind of switching device are very tedious. It must use more pieces of controlling chips to reach the purpose of control. Taking a “2 to 1” switch as example, at least two universal serial buses (USBs) must be applied, the controlling software programs are very complicated, and its price is also much more expansive.
Please refer to FIG. 1, which is a system illustration taking a “2 to 1” device according to the prior arts as an example. The hosts AP0 and AP1 of the user side, through the output ports of the terminal of a universal serial bus (USB), may be connected to a sharer 11, which is passed and transferred by a multiplexer 15 to make the host AP1 of the connection side connected to a universal serial bus-hub 12 (USB-HUB), wherein the hub itself has a controlling IC, under which is connected to a USB controlling chip 13 and a USB output end 16 and, through a device connection port 17, a further connection is made to an external USB accessory device, such as the devices of printer, digital camera, etc. (not shown in the figure), while the host AP0 of non-connecting side is then connected to a USB controlling chip 14.
Above device output end 16 may be randomly connected to the external USB device, such as: printer, mouse, or scanner, etc. However, the USB controlling chip must be installed at the computer side and controlled under both the relative driving program defined by the USB controlling chip and the software responsible for switching, so the switching instruction may be directly transferred through the USB controlling chip from the AP0 or AP0 host of the user side to order the multiplexer to switch the computer of the connection side, for example, switching the original host AP1 to the host AP0.
Above sharer 11 of “2 to 1” type applies two USB controlling chips and one hub IC and, similarly, a “3 to 1” sharer needs three USB controlling chips and one hub IC and, in the same way, a “N to 1” sharer has to use N pieces of USB controlling chips and one hub IC. Besides the applied parts are more, its controlling software is also more complicated, and it has a restriction caused by the specifications, such as USB 1.1 being unable to be compatible with USB 2.0.
Besides above shortcomings, the prior sharer also has certain popular problems. For example, when a switching instruction is executed, the original host of the connection end—such as AP1 using the accessory device must be ordered to be off line, then the host AP0 of the connection end may make a connection order, such that a great risk is created for the user. For example, if the user shuts off the host AP1 that is still on line with a printer, then it is impossible for another user of the host AP0 to use the printer commonly, and the user of the host AP0 must restart the host AP1 to make an order of cutting off, such that he can make an on line order from the host AP0. This procedure is more inconvenient than the switching function made by hand.